1. Field of the Invention
The present invention is related to a uniform curved structure of a rightness unit for a brightness enhancement film applied to a display. More particularly, the present invention is related to a brightness enhancement film having uniform curved surfaces to form enhancement units that improve entire optical characteristic.
2. Description of the Related Art
Referring to FIG. 1, International Patent Publication No. WO 96/23649 discloses a brightness enhancement film including a base 1 and a plurality of prisms 2 juxtaposed in order on the base 1. Each of the prisms 2 consisted of a first flat facet 2a and a second flat facet 2b adapted to refract light to condense light.
However, the first flat facet 2a and the second flat facet 2b are flat surfaces different from curved surface and thus only able to refract light in one dimension with respect to a top horizontal surface of the brightness enhancement film. Namely, the brightness enhancement film is only able to condense light in one dimension as well as one-dimensional refraction.
Referring to FIG. 2, U.S. Pat. No. 6,277,471, issued on Aug. 21, 2001 to Tang, discloses an another brightness enhancement film including a base 11 and a brightness layer 12. The base 11 has a top surface and a bottom surface. Also, the brightness layer 12 has a top surface and a bottom surface. A plurality of rippled ridges 121 are juxtaposed in order and each of which is consisted of brightness units 122 arranged in order. Each of the brightness units 122 is consisted of a pair of curved surfaces which may refract light in two dimensions so that the brightness unit 122 is able to condense light in two dimensions. Structurally, the bottom surface of the brightness layer 12 is adhered to the top surface of the base 11 to form the brightness enhancement film.
Referring again to FIGS. 1 and 2, U.S. Pat. No. 6,277,471 achieves condensing light in two dimensions by replacing the flat facets 2a and 2b of WO 96/23649 with the curved surfaces of brightness units 122. Therefore, U.S. Pat. No. 6,277,471 improves drawback of WO 96/23649 that merely condenses light in one dimension.
Referring again to FIG. 2, the brightness unit 122 is consisted of a first curved surface 123 and a second curved surface 124 whose curvature able to refract light in two dimensions that the condensing function is accomplished. The first curved surface 123 and the second curved surface 124 slope gently toward the top surface of the brightness layer 12 so that bottom edges of the first curved surface 123 and the second curved surface 124 are commonly terminated at a straight bottom edge 125. The straight bottom edge 125 is located between the two adjacent brightness units 122 and the straight bottom edges 125 are serially connected each other to form a wave trough.
Generally, the curvature of the first curved surface 123 and the second curved surface 124 are able to refract light for condensing. However, the first curved surface 123 and the second curved surface 124 are sloped gently toward the straight bottom edge 125, and thus the surface adjacent to the straight bottom edge 125 is performed nearly a horizontally flat surface. The slightly curvature of the flat surface is inadequate to refract light in two dimension. Although the first curved surface 123 and the second curved surface 124 are able to refract light in two dimensions, the surface adjacent to the straight bottom edge 125 may reduce entire refractive efficiency of the brightness unit 122.
The present invention intends to provide a uniform curved surface structure of a brightness unit for a brightness enhancement film. Each of the brightness units comprise a curved surface uniformly extended downward to terminate at a curved bottom edge so as to form a uniform curvature of the curved surface for increasing entire refractive efficiency in two dimensions in such a way to mitigate and overcome the above problem.
The primary objective of this invention is to provide a uniform curved surface structure of a brightness unit for a brightness enhancement film, which comprises a curved surface uniformly extended downwardly to form a curved bottom edge with uniform curvature so as to increase entire refractive efficiency in two dimensions.
The secondary objective of this invention is to provide brightness units for a brightness enhancement film, which are arranged in disorder so as to reduce morie phenomenon.
The brightness enhancement film in accordance with the present invention comprises a top surface, a bottom surface and a plurality of brightness units arranged to form an array on the top surface. The brightness unit is consisted of a first cured surface and a second curved surface. Each of the first cured surface and the second curved surface is extended downward to terminate at a curved bottom edge so as to form a uniform curvature of the curved surface.
Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description and the accompanying drawings.